Re: sniff mode

Marcel Holtmann
2009-08-24T18:40:57Z

Hi Luiz,

> It is just me or hci_conn_enter_active_mode will never do what its
> name suggests. This check will always succeed:
>
> if (conn->mode != HCI_CM_SNIFF || !conn->power_save)
> goto timer;

so conn->power_save is used to disable automatic sniff mode for incoming
connections. Mainly HID since they manager it by themselves.

> But in hci_mode_change_evt whatever mode different than HCI_CM_ACTIVE
> reset power_save to zero:
>
>
> if (!test_and_clear_bit(HCI_CONN_MODE_CHANGE_PEND, &conn->pend)) {
> if (conn->mode == HCI_CM_ACTIVE)
> conn->power_save = 1;
> else
> conn->power_save = 0;
> }

And again, we are not setting the sniff mode. We disable automatic sniff
mode feature.

> So it seems that if mode is SNIFF power_save is 0, so this check will
> only fail if mode is in fact HCI_CM_ACTIVE, and then latter on we got
> this:
>
>
> if (!test_and_set_bit(HCI_CONN_MODE_CHANGE_PEND, &conn->pend)) {
> struct hci_cp_exit_sniff_mode cp;
> cp.handle = cpu_to_le16(conn->handle);
> hci_send_cmd(hdev, HCI_OP_EXIT_SNIFF_MODE, sizeof(cp), &cp);
> }
>
> I was expecting that only when mode is HCI_CM_SNIFF it would send
> HCI_OP_EXIT_SNIFF_MODE, or Im missing something?

This reads as if NO mode change is pending, then exit from sniff mode.

Regards

Marcel